Adhesives and particularly pressure sensitive adhesives are routinely used in conjunction with a wide array of medical articles to attach or retain articles to human skin. For application to the skin, fluid handling capacity of the adhesive should be sufficiently high so that the article can be maintained in place for an extended period of time without creating skin maceration and so that good adherence to the skin can be maintained.
Fluid handling capacity of an adhesive is a function of moisture vapor transmission rate (MVTR) and static absorption characteristics of the adhesive. Typically, maintaining a high fluid handling capacity can be achieved by varying both or only one of the two properties independently.
Antimicrobial adhesives are known. However, certain antimicrobial agents degrade into undesirable compound(s). Therefore, the composition and processing conditions of an antimicrobial adhesive are important to maintain stability and avoid generation of undesirable compounds. In certain applications, it is desirable that the adhesive achieve high antimicrobial efficacy in a short time frame correlating to their clinical use.
Adding antimicrobial agent within an adhesive typically impairs adhesion. Thus, in order to obtain sufficiently high antimicrobial efficacy and adhesive properties, the coat weight of the adhesive is increased. Increased coat weight yields higher antimicrobial concentration per surface area and promotes maintenance of adequate adhesion. However, increasing adhesive coat weight impairs the moisture vapor transmission rate and therefore the fluid handling capacity of the adhesive.
In order to obtain adequate antimicrobial efficacy, high concentrations of antimicrobial agents can be required. This tends to generate toxicity to the skin. It is therefore highly advantageous for antimicrobial adhesives to generate high log reduction of microbial activity throughout a 7 day period without generating cytotoxic side effects.
Certain antimicrobial agents, chlorhexidine being one of them, are unstable over time and/or at temperatures typically required to process solvent adhesives. The instability of chlorhexidine is evident by the generation of para chloroaniline or p-chloroaniline. It is therefore advantageous to formulate a chlorhexidine containing adhesive such that the adhesive exhibits stability over time and/or at typical processing temperatures, and maintains a relatively low content of p-chloroaniline.
In certain applications, it is desirable that the adhesives achieve relatively high release rates and/or extents of release of antimicrobial agents incorporated in the adhesive. High release rates and/or extents of release of antimicrobial agents in relatively short time periods can be a prerequisite for medical incise films or peripheral IV dressings, for example.
One of the challenges in developing antimicrobial adhesive is to achieve the right balance of antimicrobial concentration in the adhesive to get the right antimicrobial efficacy as well as maintain the right adhesive properties. When increasing the amount of antimicrobial agent in an adhesive the adhesive properties tend to decrease. It is therefore important to obtain relatively high release rates and high percentage of CHG release versus the content of antimicrobial agent in the adhesive. High antimicrobial efficacy and high CHG release ratio over relatively short time periods can be a prerequisite for medical incise films or peripheral IV dressings, for example.
Accordingly, adhesives which exhibit relatively high stability and antimicrobial efficacy and yet good fluid handling capacities are needed. Also, a need remains for an improved adhesive having enhanced release characteristics. In addition, strategies for achieving these somewhat offsetting or opposing characteristics are also needed.